BACKGROUND Although the relationship between cardiac wavelength (lambda) and path length importantly determines the stability of reentrant arrhythmias, the physiological determinants of lambda are poorly understood. To investigate the cellular mechanisms that control lambda during reentry, we developed an experimental system for continuously monitoring lambda within a reentrant circuit with the...

We prove that the diagonally pivoted symmetric LR algorithm on a positive definite matrix is globally convergent. The “symmetric” or “Cholesky” LR iteration is a fairly old method of eigenreduction of a positive definite Hermitian matrix H. It reads H = H0 = R∗ 0R0 H1 = R0R 0 = R ∗ 1R1 .. (1) This process is linearly convergent [6], [5]. Recently, its singular value ’implicit’ equivalent R∗ k =...

The dual simplex method is frequently the most efficient technique for solving linear programming (LP) problems. This thesis describes an efficient implementation of the sequential dual simplex method and the design and development of two parallel dual simplex solvers. In serial, many advanced techniques for the (dual) simplex method are implemented, including sparse LU factorization, hyper-spa...

Analogues of singular value decomposition (SVD), QR, LU and Cholesky factorizations are presented for problems in which the usual discrete matrix is replaced by a 'quasimatrix', continuous in one dimension, or a 'cmatrix', continuous in both dimensions. Two challenges arise: the generalization of the notions of triangular structure and row and column pivoting to continuous variables (required i...

BACKGROUND Anterior cruciate ligament (ACL) deficiency leads to altered stability of the knee. The purpose of this study was to compare the dynamic, rotational stability of the knee, expressed as rotational stiffness, between anterior cruciate ligament-deficient (ACLD) knees, their contralateral intact knees (ACLI) and a knee healthy control group during walking, running and 90° pivoting. We hy...

In this work we propose an approach to learn a robust policy for solving the pivoting task. Recently, several model-free continuous control algorithms were shown to learn successful policies without prior knowledge of the dynamics of the task. However, obtaining successful policies required thousands to millions of training episodes, limiting the applicability of these approaches to real hardwa...